Ooh, detailed quetsions I can't answer at work! I'll post as soon as I get home
1d2 = coin flip, or you intelligently split a dice roll how you like (even = 1, odd = 2, etc)
1d3 = 1d6 divided by 2, rounding up.
If you check the character sheet posted, I think i settled on the bite attack being no more powerful than your normal unarmed strike, so 1d2. Sorry for the confusion and going back and forth on that
The detailed abswers you are looking for shouldn't affect your action, I'll explain why when I answer the question (this Trolin set-up is perfect for showing some tactis and AoO stuff in action)
Yes, your bite attack is just an attack option like punching or swinging a torch. It just has a subtle flavour.
Non-lethal = knocks people unconscios, and easier to recover from. Lethal = normal damage, which will kill people. So if Haynuus's blow reduced the Trolin to 0, it's dead. If Westian's blow reduces it to 0, it's knocked unconscious. The damage from Westina's blow it would recover with some sleep and rest.
Your bite attack does lethal damage. You would either have to take a penalty to do non-lethal damage, or better just use your paws for non-lethal damage:)